Effect of ice packs on the synthesis of fly ash-based geopolymer and its use in soft clay stabilization

Abstract

Ice packs are mainly composed of super-absorbent resins and have superior cooling properties compared to ice. However, they do not decompose naturally, so there is no way to recycle them except for reuse. Therefore, this study aims to develop a fly ash-based geopolymer using ice packs. Geopolymer is a material that is generated when amorphous alumina or silica-rich material is mixed with a highly alkaline solution, such as sodium hydroxide. Ice packs are mainly composed of sodium polyacrylate (PAAS), which has excellent mechanical stability, high heat resistance, and strong hydration. Alkaline activators of 3–12 M sodium hydroxide solutions were prepared using distilled water (AA(W)) and using ice packs (AA(I)). The experiment was conducted by 1) synthesis with NaOH alkaline activator, 2) finding the optimal ratio by adding sodium silicate, and 3) finding the optimal ice pack content. Then, each geopolymer was synthesized by mixing the fly ash precursor and the alkali activator and cured in an oven at 60°C. for 24 hours. Results showed that the geopolymer using the ice pack as an alkali activator showed higher compressive strength and compressive wave speed than the geopolymer using water as the activator. The optimal ratio of sodium silicate was 1, and the optimal content of the ice pack was 50%. In addition, additional experiments were conducted to apply the ice pack-based geopolymer to the soft clay stabilization. Soft clay was synthesized with AA(W) and AA(I) and compared. The strength and stiffness of the ice-pack-based geopolymer were superior to those of water, and the optimal value was shown at 9 M. In addition, soft clay stabilization was performed using a one-part geopolymer applicable to the field. Compared with the two-part geopolymer, the value of 6 M came out higher, which indicates the possibility of field application.